화학공학소재연구정보센터
International Journal of Hydrogen Energy, Vol.37, No.13, 10165-10171, 2012
Design and optimization of single particle electrodes for the kinetic analysis of hydrogen evolution and absorption on hydrogen storage alloys
In the literature, there is a large discrepancy between reported values of electrochemical, kinetic and transport parameters of hydrogen storage alloys. These discrepancies arise, because in most cases, electrodes are prepared with the powdered alloy supported within a porous matrix, constituted by carbon and additive binders such as PTFE. The main drawback, of this preparation technique, for the identification of kinetic parameters, is the uncertainty in the specific active area value, where the hydrogen evolution and absorption processes take place. To overcome the disadvantages described, a new type of electrode, was designed, using a single particle of AB(5) and AB(2) hydride forming alloys. The data obtained from electrochemical impedance measurements were adjusted in terms of a physicochemical model that takes into account the processes of hydrogen evolution and absorption coupled to hydrogen diffusion. From the study it can be concluded that the differences in the behavior of the AB(5) and AB(2) alloys, presenting the first best performance during the activation and operation at high discharge currents, are mainly due to higher values of the exchange current density and the diffusion coefficient of H for the AB(5) alloy. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.